TEST 2: Testing Fuel Pressure With A Fuel Pressure Test Gauge
The most accurate way to test the fuel pump on your 2.2L Ecotec equipped GM car is with a fuel pressure test gauge.
The fuel pressure test gauge can be easily connected to your car's fuel system via the Schrader valve on the fuel injector rail. This Schrader valve is very easy to get to and in plain sight on the fuel injector rail.
If you don't own a fuel pressure gauge, you can rent one from your local auto parts store (AutoZone, O'Reilly Auto Parts). If you're interested in buying your own, check out my recommendations here: Which And Where To Buy A Fuel Pressure Gauge.
OK, let's get started with this test:
Connect the fuel pressure gauge to the Schrader valve on the fuel rail.
With a shop towel, mop up any fuel that was released during the process of connecting the fuel pressure test gauge.
When ready, ask your helper to cycle the key on and off (but don't start the engine) while you observe the fuel pressure tester's gauge.
Your fuel pressure gauge should register between 53-59 PSI (if the fuel pump is working correctly).
NOTE: The fuel pressure specification of 53-59 PSI is with the key on but engine off (KOEO).
OK, now that the testing part is done, let's take a look at what your results mean:
CASE 1: Fuel pressure test gauge registered 0 PSI or anything under 53-59 PSI. This test result tells you that the fuel pump is not working correctly.
Now, I usually take one more precaution, before condemning the fuel pump as BAD and this is to check that the fuel pump is getting 12 Volts as the engine is cranking. This is just to make sure that the fuel pump relay and fuse are OK and doing their job.
What you'll have to do to accomplish this is to attach a multimeter in Volts DC mode to the wire that supplies this voltage to the fuel pump and while a helper cranks the engine, verify that the fuel pump is getting this power. If the 12 Volts are being supplied to the fuel pump then you have now 100% verified that the fuel pump is fried and needs to be replaced.
CASE 2: Fuel pressure test gauge registered between 53-59 PSI. This is the correct and expected test result and tells you that the fuel pump is OK.
Is The Anti-Theft System Causing The No Start Condition?
One of the most common problems, that will keep your GM car from starting, is a factory anti-theft system failure. If you haven't experienced this problem yet, you will (it's akin to death and taxes for any GM vehicle owner).
The anti-theft system on your 2.2L Ecotec equipped car is known as the PASS-Key/Passlock system. When an anti-theft system component fails, you car will crank but not start or start momentarily and then die. This no start condition can seem like it's due to a bad fuel pump.
To explain this a bit further: the anti-theft system is designed to disable the fuel injectors (when it activates) the 3 seconds after the engine starts. This causes the engine to stall and if you use starting fluid, the engine will start (and of course die when the dose of starting fluid you just sprayed gets consumed).
This may lead you to believe that the fuel pump has failed (when it hasn't). To help you tell the difference between a bad fuel pump and an anti-theft system problem take a look at the following chart:
|Anti-Theft Versus Fuel Pump|
|Symptom||PASS-Key / PassLock||Fuel Pump|
|Engine cranks but won't start||YES||YES|
|Engine starts with starting fluid (momentarily)||YES||YES|
|Ignition system delivers spark||YES||YES|
|Anti-theft MIL flashes on instrument cluster||YES|
|Engine starts momentarily then stalls||YES|
|Fuel pressure at spec (as checked
w/ fuel pressure gauge)
|PCM disables fuel injectors a few
seconds after the engine starts
Where To Buy A Fuel Pressure Test Gauge
One of the most important tools any serious DIY'er should have in his/her tool box is a fuel pressure test gauge. The cool thing is that you can buy them in just about any auto parts store (although at a higher price).
The following fuel pressure test gauge kits are pretty good deals and will connect to the 2.2L Ecotec engines covered by this tutorial:
All of the fuel pump pressure test kits above have the fitting that will connect to your 2.2L Ecotec engine's fuel injector rail.
Where To Buy The Fuel Pump And Save
The fuel pump in your 2.2L Ecotec equipped GM car is located inside the fuel tank. The fuel pump can be bought in any auto parts store, but I think you'll find the better price online. The following fuel pumps are pretty good deals: